Process of pulping and defibering paper stock and apparatus therefor



Feb. 21, 1967 w. c. TOMLINSON 3,305,180

PROCESS OF PULPING AND DEFIBERING PAPER STOCK AND APPARATUS THEREFOR Z5 Sheets-Sheet 1 Filed Jan. 28, 1964 LARGER PARTlCLES IN V EN TOR.

WILLIAM C. TOMLINSON 26 SMALLER Fl G 2 PARTICLES} ATTORNEYS Feb. 21, 1967 w. c. TOMLIN N 3,305,180

PROCESS OF PULPING AND DE ER PAPER STOCK AND APPARATUS THERE Filed Jan. 28, 1964 5 Sheets-Sheet 2 FIG.4

FIG?

XV IO -42 @H FIG 8 4O 58 38 IO INVENTOR.

WILLIAM C. TOMLINSON BY ATTORNEYS Feb. 21, 1967 w. c. TOMLINSON 3,305,180

- PROCESS OF PULPING AND DEFIBERING PAPER STOCK AND APPARATUS THEREFOR Filed Jan. 28, 1964 s Sheets-Sheet 5 FIGII INVENTOR.

WILLIAM C. TOMLINSON BY ATTO R N EYS United States Patent 3,305,180 PROCESS OF PULPING AND DEFIBERHNG PAPER STOCK AND APPARATUS THEREFOR William Clyde Tomlinson, Williamstown, Mass., assignor to The Noble & Wood Machine Company, HOOSlCk Falls, N.Y., a corporation of New York Filed Jan. 28, 1964, Ser. No. 340,753 4 Claims. (Cl. 24114) This application is a continuation-in-part of my copending application for Pulper, Serial No. 73,671, filed December 5, 1960, now abandoned.

This invention is an improvement in pulping machinery and more particularly in means for extracting pulp from a pulper, which means simultaneously select the pulp to be withdrawn and also act to further refine oversize pieces of pulp.

In the manufacture of paper and similar art1cles, it is customary to produce a pulp slurry from pulp laps, paper, and the like by the mechanical action of an apparatus commonly known as a pulper. The process is accomplished by continued agitation of the ingredients in water, until the solid agglomerates have been reduced sufficiently in size for use in the paper making furnish.

Many types of pulpers have been designed, but a problem generally encountered in their use has been that of properly removing the pulp from the pulper after it has been reduced. Pulping by batches has been customary but it is somewhat inefficien-t and does not combine well with continuously operating modern paper making equipment.

One attempt to pulp on a continuous basis has been to provide an outlet orifice in the pulping tank fitted with a screen over its mouth. The screen satisfactorily prevents large particles from leaving the vat, but simultaneously tends to become clogged. Pulping on a continuous basis, therefore, has not been altogether satisfactory.

Accordingly, it is an object of my invention to provide a pulper from which the pulp may be continuously with drawn in proper condition for use in a paper making furnish without shutting down the machine or clogging the exit orifice.

It is another object of my invention to provide means for withdrawing the pulp from the pulper without requiring screens or other similar means for particle size selection.

It is a further object of my invention to provide a pulper which may be operated on a continuous basis and which will include adjustable means for varying particle size selection.

In the practice of my invention, in a preferred embodiment thereof, I employ a pulper comprising a tank or tub with a substantially flat bottom having a circular rotor segment therein. On the rotor segment I mount impeller blades which create vigorous fluid acceleration and shearing primarily in an upward direction. Adjacent to the impeller blades and also mounted on the rotor segment, I provide a set of lateral ejector blades comprising upstanding flanges which eject the pulp radially from the impeller blades across the bottom of the tank. A narrow annular outlet orifice is provided between the rotor segments and the adjacent areas of the tank bottom and opposed refining elements are mounted in this annular outlet orifice. In operation, the stock is violently agitated in a generally upward path by the impeller blades and laterally ejected by the ejector blades simultaneously. The larger materials, not yet broken down, tend to be caught up in a vortex flow pattern thus created, While the more finished pulp tends to flow outwardly across the rotor segment. When the more finished pulp passes over the annular outlet orifice between the rotor segment and the tank bottom, some of it is drawn down through the opening and carried out of the pulper. Generally speaking, the larger and less refined particles will tend to carry across the entrance to the annular opening and this action automatically provides a degee of particle selection. The positioning of the outlet orifice adjacentto the rotor segment therefore provides the first step in the selection of pulp which is to be withdrawn. The pulp which enters the annular outlet orifice is not, however, of uniform size. A substantial portion of the pulp is pulped to satisfactory size; however, a small portion is likely to be still oversize. Therefore, I employ a set of refiner elements positioned in the annular outlet orifice in such fashion that they only refine the oversized pieces of stock. Several different configurations of these refiner elements may be employed, including vertical, beveled, or radial of multiple combinations of each.

The vertical form is preferred, but in one embodiment of my invention I construct the rotor segment as a truncated conical segment and hence vertical adjustment of the rotor segment with relation to the tank bottom results in adjustment of the spacing of the refining elements attached to the rotor segment and the tank bottom and consequently changes the particle size which is allowed to pass through the annular outlet orifice. In the preferred embodiment of my invention in which the refiner elements are vertically disposed, the spacing between the refining elements would not be affected by vertical adjustment of the rotor.

Although my pulper is well suited for continuous pulping, it should be noted that it may also be used as a batch pulper. When so used the smaller particles of pulp pass through the annular outlet orifice and are returned to the tank. The refining elements disposed in the orifice cause further defibering of the smaller particles. In pulpers heretofore used in batch operations, the smaller particles were not treatment but were left in the tank where the only defibering action to which they were subjected was the relatively mild action of the pulping blades. This therefore constitutes a distinct and important feature of my invention applicable specifically to batch type operations.

The features of my invention include that the apparatus may be operated continuously for pulping operations, that the pulping outlet orifice is self cleaning and that particle size selection is automatic.

Another feature of my invention is that the refining elements in the outlet orifice are spaced primarily for reducing the size of oversized particles entering the outlet orifice. Thus the refining action applies primarily only to a portion of the stock passing through them.

These and other objects and features of my invention will appear as the description proceeds with the aid of the accompanying drawings, in which:

FIG. 1 is a view of the pulper in side elevation with part of the tank wall cut away and showing the rotor segment and part of the tank bottom in cross-section;

FIG. 2 is a fragmentary view of one embodiment of the pulp extracting means in vertical cross-section showing vertical refiner elements in place;

FIG. 3 is a fragmentary plan view of the pulp extracting means showing vertical refiner elements of rib design;

FIG. 4 is a plan view of the rotor segment and a portion of the tank bottom of the pulper of FIG. 1;

FIG. 5 is a fragmentary cut away view in perspective of the pulp extracting means showing vertical refining ribs attached to the rotor segment and slanted refining ribs attached to the tank bottom;

FIG. 6 is a fragmentary cut away view in perspective subjected to this further of the pulp extracting means showing rounded refiner elements in place;

FIGS. 7, 8, 9, and are fragmentary views in vertical cross-section of alternative embodiments of the refining elements disposed in the pulp extracting means; and

FIG. 11 is a plan View of the rotor segment and a portion of the bottom of the pulper tank showing an alternative configuration of the pulping blade arrangement having solely ejector blades.

Having reference to the accompanying drawings for a more particular description, I position a circular rotor element 10 in the bottom 14 of a suitable tank 12. The rotor element 10 forms a rotatable segment of the tank bottom 14 and is supported on a shaft 16 which is mounted for rotation in suitable bearings 18. The shaft 16 and associated rotor element 10 are engaged for rotation by an electric motor and belt drive system indicated generally at 20.

Mounted on the rotor element It), and extending tangentially from the shaft 16 are a multiplicity of impeller blades 22. In the preferred embodiment of my invention six impeller blades 22 are employed. The configuration of each impeller blade 22 is generally that of a vertically disposed right triangle, the hypotenuse being curved downwardly from the shaft 16.

The rapid rotation of the rotor element 10 and the associated impeller blades 22 causes the pulp stock to move violently within the tank, thereby breaking down the larger pieces of stock. Simultaneously forces are set up in the stock and water mixture which tend to create a vortex over the rotor element 10. As a result, the larger pieces of stock, those not yet SllfilClGIltlY reduced in size, tend to flow upwardly in the field of the vortex and thereafter fall back for further pulping. This impeller blade action is a feature of my preferred embodiment, but it will be seen in FIG. 11 that my alternative embodiment is constructed without the impeller blades. It has been found that the employment of impeller blades on the rotor increases the efficiency of the over-all performance of the pulper, but is not absolutely necessary to satisfactory pulper performance.

The smaller pieces of stock which comprise the more finished pulp are not as easily caught up in the vortex field and tend to flow radially from the shaft 16, and impeller blades 22.

In order to assist this tendency of the more finished pulp to move radially over the rotor element 10, and not to be caught up in the vortex field, a plurality of lateral ejector blades 24 are formed of right-angled sections of steel or other suitable material, and are mounted to present an upstanding blade element. The lateral ejector blades 24 are constructed to decline slightly from their leading end-s to their trailing ends and at their highest point are of less vertical dimension than the impeller blades 22. The lateral ejector blades 24 are oriented in two concentric circles coaxial with the shaft 16 and assume positions turned slightly from the tangential to the two concentric circles, their leading ends being closer to the shaft 16. In the preferred embodiment of my invention three lateral ejector blades 24 are positioned on each circle, spaced 120 apart. The two circles of lateral ejector blades 24 thus formed are oriented such that one lateral ejector blade 24 is located every 60 around the rotor element 16. In operation, therefore, the rotor element It impeller blades 22 and lateral ejector blades 24 cooperate to throw the larger stock upwardly in the tank, and push the more finished pulp radially over the rotor element 10 and along the tank bottom 14.

In order to withdraw the more finished pulp from the pulper before it is again intermixed with the larger pieces of stock, an annular outlet orifice indicated generally at 26 is provided between the rotor element 10 and the tank bottom 14. The annular outlet orifice 26 is initially provided by constructing an opening in the tank bottom 14 with a larger radius than that of the rotor element 10. Thus when the rotor element 10 is in place, an annular outlet orifice will be formed adjacent to the rotor element 10. In the beveled rotor embodiment of my invention, the rotor element 10 has an inwardly and downwardly sloping circumferential edge indicated at 32 in FIG. 8 and the tank bottom 14 has a cooperating edge indicated at 34 so as to form a sloping annular passage having parallel faces 32, 34. Preferably, however, the annular faces 32, 34 comprise two series of annular face plate segments 38, 49. The annular face plate segments 38 are attached by bolts or other suitable means to the rotor segment 10, and combine to form the annular face 32. The annular face plate segments 40 are similarly attached to the tank bottom 14 and combine to form the annular face 34.

In the embodiment of my invention shown in FIG. 8, the annular faces 32, 34 are provided with a multiplicity of vertical refiner ribs 42 formed by milling lateral grooves 44 in the annular face plate segments 38, 4!). The ribs 42 are provided for the purpose of further refining oversize particles of pulp which enter the annular outlet orifice 26. In operation, the ribs 42 do not, however, actually out the stock fibres as is the case in a true refiner as hereina-fter described. The space between opposing ribs is greater than would be normal for refining, and the fibres are not subjected to comparable pressures.

By employing ribs 42 and grooves 44, an annular face configuration results in which there are pockets, namely the grooves 44, in which the larger pieces of stock admitted into the annular outlet orifice 26 are thrown about causing them to further break-down. In addition, any small particles of dirt carried into the annular outlet orifice 26 tend to be dispersed by the action of the ribs 42. Very little dirt actually enters the annular outlet orifice 26, as will be hereinafter explained.

As well as being thrown about within the grooves 44 the oversized particles of stock are thrown from groove to groove thereby accelerating the further break-down of the particles.

It is to be noted that the described configuration of ribs 42 and grooves 44 may be successfully varied. One obvious variation would be to position the ribs 42 on the tank bottom 14 at an angle to the ribs 42 on the rotor element 10 (see FIG. 5). If the ribs 42 on the tank bottom 14 are canted in the same direction as those on the rotor element 10, it results in a pumping action between the rotor element 10 and the tank bottom 14 which may or may not be desirable depending upon the desired condition of stock flow adjacent to the annular outlet orifice 26.

Another of the possible configurations for the refiner ribs 42 is that the ribs 42 and grooves 44 be milled so as to provide rounded surfaces rather than sharp corner edges (see FIG. 6).

In the preferred embodiment of my invention the refining elements in the annular outlet orifice 26 are vertiialiy disposed rather than slanting inwardly (see FIGS.

The principal advantage to constructing the annular outlet orifice 26 at a sloping angle is that vertical movement of the shaft 16 and associated rotor element 10 may then be achieved relative to the tank bottom 14 which will change the width of the annular outlet orifice 26 and thereby provide means for varying the particle size which may be admitted into the annular outlet orifice 26. Such vertical adjustment of the shaft 16 may be accomplished by various conventional mechanisms (not shown).

Positioned directly beneath the rotor element 10 and tank bottom 14 and communicating with the tank 12 through the annular outlet orifice 26 is a receiving chamber 36. The more finished pulp flows through the annular outlet orifice 26 into the receiving chamber 36 and from there it passes through a side opening 39 in the receiving chamber 36 to a pumping station indicated generally at 41 whereby it is returned to the top of the tank and/or forced on to the succeeding process area. It is to be noted that the more finished pulp not only drops into the annular outlet orifice 26 as it passes radially over the rotor element under the forces of pump means 41 and gravity, but also is drawn into the annular outlet orifice 26 by suction forces created at the opening 26 by the rotation of the rotor element 10 in close proximity to the stationary tank bottom 14.

In the preferred embodiment of my invention two scraping members 46 are attached to the rotor element 10. The scraping members 46 are flat steel members which are positioned slightly above and protrude over the annular outlet orifice 26, serving to dislodge any large pieces of stock or foreign matter which happen to accumulate there and might otherwise clog the annular outlet orifice 26. In practice the scraping members 46 are positioned 180 apart around the circumference of the rotor element 10.

The operation of my pulper is as follows:

The materials to be pulped, paper, pulp laps, etc., are placed in the tank 12 and water is continuously added. The rotor element 10 is then caused to rotate at high speed. The rotation of the impeller blades 22 causes the stock mixture to be set in motion. The various solid materials in the stock mixture are thrown violently against each other and against the tank 12 and rotor element 10 thereby breaking down and combining with the water to form more finished pulp.

The rapid rotation of the rotor element 10 sets up two separate fields of motion in the stock. The larger pieces are given an upward thrust by the impeller blades 22 and tend to form a vortex over the rotor element 10. The more finished stock is smaller and tends to flow radially away from the shaft 16 of the rotor element 10 rather than to be caught up in the vortex field. The lateral ejector blades 24 take advantage of the tendency of the pulp to flow radially along the rotor element 10 and urge the pulp more strongly toward the periphery of the rotor element.

Once the pulp has reached the periphery of the rotor element 10 a portion of it passes into the annular outlet orifice 26 from which it ultimately passes into the receiving chamber 36 and subsequently out of the pulper. It is to be noted that the relative spacing of the side Walls of the annular outlet orifice 26 effects a preliminary selection of particles which will be admitted into the annular outlet orifice 26. Of those particles which are admitted, some of them, a large majority, pass easily into the receiving chamber 36. Some of the particles which are admitted are, however, too large to be useful in the succeeding process steps, and therefore, they are further refined by the action of the refining ribs 42 and grooves 44.

It should also be noted that dirt and other foreign matter tends, in operation, to be carried beyond the annular outlet orifice 26 and consequently does not pass out with the more finished pulp. If any pieces of foreign matter or large pieces of stock should clog the annular orifice 26 they are quickly removed by the scraping members 42.

It will now be apparent to one skilled in the art that several modifications of my invention may be made. Among them, the refining elements disposed in the annular outlet orifice 26 may be constructed horizontally rather than vertically or beveled as above described. Horizontal refining elements comprising annular V-shaped ribs 48 and V-shaped grooves 50 (see FIG. 7) may be employed, and may be spaced apart or caused to intermesh depending on the degree and type of refining action desired. Instead of V-shaped ribs 48 and grooves 50, annular ribs 52 and cooperating annular channels 54 having a substantially square cross-section may be formed (see FIG. 9). Both of the above-mentioned configurations of refining elements have an advantage over vertically disposed refining elements. This advantage is that although the small particles of pulp readily pass downwardly through the annular outlet orifice, the oversize particles are retained in the refining area in the V-shaped grooves 50 or channels 54 until sufficiently reduced in size to pass out of the refining area.

A further modification of the horizontally disposed refining elements is shown in FIG. 10 wherein the refining elements 56 disposed on the rotor segment 10 are arranged in a step configuration while those on the tank bottom 14 are arranged both as cooperating steps 58 with or without channels 60. The step configuration permits vertical adjustment of the rotor segment 10 in relation to the tank bottom 14 which adjustment varies the spacing in the annular outlet orifice thereby providing means for selecting the maximum pulp size to be admitted, as well as the maximum size to be passed through without refining.

It will be understood that numerous modifications of the foregoing detailed description of my invention will be apparent to those skilled in the art, and therefore, I wish to emphasize that the combination of the ejector blades 24 on the rotor and the annular outlet orifice adjacent thereto having spaced refining means therein in opposed relation on the rotor and stator respectively, is the basic and most important combination of elements of my invention. Accordingly, I wish to make clear that I claim this combination by itself, and for this purpose in FIG. 11 I have shown this relationship of elements without the pulper blades 22. Such an arrangement works entirely satisfactorily, particularly if the re-circulating pump 41 is operated so that the unpulped, large particle sized stock at the topof the tank is driven successively downward toward the rotor by the action of the re-circulated stock pouring downwardly thereon. Thus it will be seen that the combination of the foregoing elements together with the re-circulation apparatus is also important, and I intend to claim it broadly both as an apparatus and in relation to the process carried out with it involving the downward action on the stock.

Having thus described and illustrated preferred and modified embodiments of my invention, what I claim as new, and desire to secure by Letters Patent of the United States is:

1. Combined pulping and defibering apparatus comprising, a pulping tank having a bottom wall, substantially vertical walls forming a central annular opening in said tank bottom, a rotor mounted for rotation in said annular opening, pulping blade means on said rotor for directing stock in said tank in an upward vortical path, ejector blade means on said rotor for ejecting stock from said rotor in a tangential-radial path, the periphery of said rotor and the said vertical wall of said annular opening defining between them an annular outlet orifice opening directly into said tank at a point where said tangentially-radially ejected stock leaves the periphery of said rotor, and cooperating means mounted respectively on said rotor and said wall in said annular orifice for defibering said stock, said latter means being respectively spaced to reduce the size only of oversized particles in said annular orifice.

2. The process of pulping and defibering paper stock comprising, forming an aqueous suspension of unpulped paper stock, subjecting said stock in a tank to a rotor action in which said stock is urged in a tangential-radial path from a rotor across an annular outlet orifice, withdrawing part of said stock through said annular outlet orifice, refining said stock in said annular outlet orifice by the action of refining means spaced sufficiently close to refine over-size particles but sufficiently apart to avoid substantial refinement of particles of the correct size, recirculating said withdrawn stock into the top of said tank, and directing said re-circulated stock downwardly against the stock in said tank to drive stock at the top thereof downwardly in said tank toward said rotor.

3. Combined pulping and defibering apparatus comprising;

(a) a pulping tank having a bottom wall in which a central aperture is formed,

(b) a stator wall formed on the inner periphery of said centrally apertured tank bottom wall,

(c) a rotor positioned Within said central aperture and 3 mounted for rotation, said rotor having a rotor wall formed on the periphery thereof spaced from and in concentric relation with said stator Wall forming an annular outlet orifice therebetween, said orifice being uncovered and opening directly into said tank at said rotor periphery,

(d) blade means mounted on the upper surface of said rotor spaced from the stator Wall for throwing stock in a tangential-radial direction across said annular outlet orifice thereby creating a recirculating current Within said tank,

(e) pumping means in series connection with said annular outlet orifice for continuously Withdrawing from said tank a portion of the stock thrown across said annular outlet orifice, and

(f) cooperating refining means mounted respectively on said rotor and stator walls within said annular outlet orifice, said cooperating refining means being spaced sufiiciently apart to reduce the size only of oversized stock particles being Withdrawn through said annular outlet orifice. 4. Apparatus of claim 3 further characterized by recirculating means in series connection With said pumping 5 means and the interior of said pulping tank for reintroducing Withdrawn stock into said tank.

References Cited'by the Examiner UNITED STATES PATENTS WILLIAM W. DYER, 111., Primary Examiner.

20 ROBERT C. RIORDON, Examiner.

H. F. PEPPER, Assistant Examiner. 

1. COMBINED PULPING AND DEFIBERING APPARATUS COMPRISING, A PULPING TANK HAVING A BOTTOM WALL, SUBSTANTIALLY VERTICAL WALLS FORMING A CENTRAL ANNULAR OPENING IN SAID TANK BOTTOM, A ROTOR MOUNTED FOR ROTATION IN SAID ANNULAR OPENING, PULPING BLADE MEANS ON SAID ROTOR FOR DIRECTING STOCK IN SAID TANK IN AN UPWARD VORTICAL PATH, EJECTOR BLADE MEANS ON SAID ROTOR FOR EJECTING STOCK FROM SAID ROTOR IN A TANGENTIAL-RADIAL PATH, THE PERIPHERY OF SAID ROTOR AND THE SAID VERTICAL WALL OF SAID ANNULAR OPENING DEFINING BETWEEN THEM AN ANNULAR OUTLET ORIFICE OPENING DIRECTLY INTO SAID TANK AT A POINT WHERE SAID TANGENTIALLY-RADIALLY EJECTED STOCK LEAVES THE PERIPHERY OF SAID ROTOR, AND COOPERATING MEANS MOUNTED RESPECTIVELY ON SAID ROTOR AND SAID WALL IN SAID ANNULAR ORIFICE FOR DEFIBERING SAID STOCK, SAID LATTER MEANS BEING RESPECTIVELY SPACED TO REDUCE THE SIZE ONLY OF OVERSIZED PARTICLES IN SAID ANNULAR ORIFICE.
 2. THE PROCESS OF PULPING AND DEFIBERING PAPER STOCK COMPRISING, FORMING AN AQUEOUS SUSPENSION OF UNPULPED PAPER STOCK, SUBJECTING SAID STOCK IN A TANK TO A ROTOR ACTION IN WHICH SAID STOCK IS URGED IN A TANGENTIAL-RADIAL PATH FROM A ROTOR ACROSS AN ANNULAR OUTLET ORIFICE, WITHDRAWING PART OF SAID STOCK THROUGH SAID ANNULAR OUTLET ORIFICE, REFINING SAID STOCK IN SAID ANNULAR OUTLET ORIFICE BY THE ACTION OF REFINING MEANS SPACED SUFFICIENTLY CLOSE TO REFINE OVER-SIZE PARTICLES BUT SUFFICIENTLY APART TO AVOID SUBSTANTIAL REFINEMENT OF PARTICLES OF THE CORRECT SIZE, RECIRCULATING SAID WITHDRAWN STOCK INTO THE TOP OF SAID TANK, AND DIRECTING SAID RE-CIRCULATED STOCK DOWNWARDLY AGAINST THE STOCK IN SAID TANK TO DRIVE STOCK AT THE TOP THEREOF DOWNWARDLY IN SAID TANK TOWARD SAID ROTOR. 